During mining and beneficiation of many minerals, including energy minerals, particulates become suspended in wastewaters. Often associated with these particles are organic and inorganic trace contaminants. Before-reuse of discharge of these waters, the suspended particulates and related contaminants must be removed. The work described here is a detailed comparative study of the flocculation of coal washery effluent slurry with modified starch and a synthetic polymer under controlled conditions of pH and flocculant concentration. The degree of flocculation of the system was evaluated by the residual turbidity measurements of the settled suspensions. Results show that the flocculating reagents can significantly contribute to the existence of low settling rates at high supernatant clarity often observed in some coal washery effluent treatment by flocculation and sedimentation method. High supernatant clarify were obtained at pH above 7 for the modified starch and above pH 9 for the synthetic polymer. Optimum polymer dosage which maximized the degree of slurry flocculation was found to be about 65 ppm and 0.4 ppm for the modified starch and synthetic polymer respectively. Both flocculants gave good clarification but the synthetic polymer was much more effective. The study further reveals that in some slurry-polymer systems, fast settling corresponds to high Sediment Volume whereas in others the opposite applies. It is concluded that for proper design and operation of such treatment facilities, this phenomenon should be taken into consideration.